Sains Malaysiana 43(6)(2014): 833–842

 

Characteristics of Nanostructured CaxZn(1-x)Al2O4 Thin Films Prepared by Sol-Gel Method

for GPS Patch Antennas

(Ciri Filem Nipis CaxZn(1-x)Al2O4 Berstruktur Nano yang Dihasilkan Melalui Kaedah

Sol-Gel untuk GPS Tampalan Antena)

WAN NASARUDIN WAN JALAL1, HUDA ABDULLAH1*, MOHD SYAFIQ ZULFAKAR1, SAHBUDIN SHAARI2, MOHAMMAD THARIQUL ISLAM3& BADARIAH BAIS1

 

1Department of Electrical, Electronic and System Engineering, Faculty of Engineering and Built Environment, Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor, Malaysia

 

2Institute of Microengineering and Nanoelectronics (IMEN), Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor, Malaysia

 

3The Institute of Space Science (ANGKASA), Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor, Malaysia

 

Received: 28 March 2013/Accepted: 2 February 2014

 

ABSTRACT

CaxZn(1-x)Al2O4 thin films (x = 0.00; 0.05; 0.10; 0.15 and 0.20) were prepared by sol-gel method with the substitution of Zn2+ by Ca2+ in the framework of ZnAl2O4. The effect of Ca addition on the structure and morphology of CaZnAl2O4 thin films was investigated by x-ray diffraction (XRD), field-emission scanning electron microscope (FESEM), energy-dispersive x-ray spectroscopy (EDX), ultra-violet visible (UV-Vis) and atomic force microscope (AFM). The XRD patterns showed the characteristic peaks of face-centred cubic (fcc) ZnAl2O4 and CaZnAl2O4. The addition of Ca increased the crystallite size from 8.9 to 30.2 nm. The bandgap of CaxZn(1-x)Al2O4 thin film was found in the range of 3.40 to 3.84 eV. SEM micrograph shows the morphology of all thin films is sphere-like, with the grain size increased from 33 to 123 nm. The AFM images show the roughness of surface morphology increased. The substitution of Zn2+ by Ca2+ increased the crystallite size, grain size and surface roughness which evidently increased the density (4.59 to 4.64 g/cm3) and dielectric constant (8.48 to 9.54). The composition of

CaxZn(1-x)Al2O4 is considered as suitable material for GPS patch antennas.

 

 Keywords: Band gap; Ca-ZnAl2O4; GPS patch antena; nanostructures

 

ABSTRAK

Filem nipis CaxZn(1-x)Al2O4(x = 0.00; 0.05; 0.10; 0.15 dan 0.20) telah dihasilkan dengan kaedah sol-gel iaitu menggantikan Zn2+ dengan Ca2+ di dalam bahan utama ZnAl2O4. Kesan terhadap penambahan Ca pada struktur dan morfologi filem nipis CaZnAl2O4 telah dianalisis dengan menggunakan pembelauan sinar-x (XRD), mikroskopi imbasan pancaran medan elektron (FESEM), x-ray serakan tenaga spektroskopi (EDX), cahaya nampak ultra lembayung (UV-Vis) dan mikroskopi daya atomik (AFM). Corak pembelauan XRD menunjukkan ciri-ciri puncak berpusat muka padu pada bahan ZnAl2O4 dan CaZnAl2O4. Penambahan Ca telah meningkatkan saiz kristal daripada 8.9 kepada 30.2 nm. Jalur tenaga bagi filem nipis CaxZn(1-x)Al2O4 ialah antara 3.40 hingga 3.84 eV. Graf mikro SEM menunjukkan morfologi bagi kesemua filem nipis adalah berbentuk butiran dengan saiz butiran meningkat daripada 33 kepada 123 nm. Imej AFM menunjukkan berlakunya peningkatan pada permukaan morfologi CaxZn(1-x)Al2O4. Penggantian Zn2+ dengan Ca2+ telah meningkatkan saiz butiran dan peningkatan kekasaran permukaan yang seterusnya memberi kesan terhadap ketumpatan bahan (4.59 kepada 4.64 g/cm3) dan pemalar dielektrik (8.48 kepada 9.54). Komposisi CaxZn(1-x)Al2O4 dianggap sebagai bahan yang sesuai untuk penghasilan GPS tampalan antena.

 

Kata kunci: Ca-ZnAl2O4; GPS tampalan antena; jalurtenaga; strukturnano

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*Corresponding author; email: huda@vlsi.eng.ukm.edu.my

 

 

 

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